Chlorine 36 age dating
And to say anything sensible, you need at least two different dating techniques, based on the characteristics of the rock.
Thus, even if it is considered that the bluestones were moved by human transport, the Chlorine-36 dates do not tell us at what era that movement might have taken place. Chlorine-36 dating British ice-sheets, Abstracts of the American Geophysics Union, 1994 Fall Meeting: 226.
We welcome further evidence in the Stonehenge debate, but are concerned about misinterpretations.
Chlorine-36 dating might help the debate by obtaining large numbers of dates on Preseli outcrops (to give a mean date of oldest exposed surfaces). Late Cenozoic Wales and south-west England, Proceedings of the Ussher Society 8: 209-13.
This finding was widely purported in the media to demonstrate conclusively that glaciation could not have moved the bluestones to Stonehenge. It does not even support the human transport theory.
Prof Bowen's dating exercise -- also involving other dates, with two from Carn Meini, has been heavily criticised by other geologists.